I. Field of the Invention
The present invention pertains to jet engines having no rotary compressor. More particularly the present invention pertains to a device for creating turbulent fluid flow into the combustion chamber or region of such a jet engine.
II. Discussion of the Background
A ramjet is a type of jet engine which includes an air inlet, combustion chamber and exhaust nozzle. The air inlet is designed to accommodate air moving at a supersonic speed. An inlet cone or body is situated within the air inlet and constricts air flow such that the received air is compressed and slows to a subsonic speed before entering the combustion chamber. For liquid-fuel type ramjets, the combustion chamber is provided with fuel injectors and flaming elements for combusting an air-fuel mixture. The combusted air-fuel mixture is then expelled through the exhaust nozzle to achieve propulsion. The ramjet has no moving parts and some have referred to it as resembling a stovepipe-type of hardware.
As previously indicated, to perform efficiently, the ramjet requires air to be input at supersonic speeds. Therefore, a ramjet-powered air vehicle must have an alternate engine or power source to initiate speeds which are sufficient in magnitude to effectively switch propulsion responsibilities to the ramjet.
FIG. 1 is a side-view cross-section of an exemplary cylindrically-shaped ramjet engine. The ramjet 10 has an inlet 12 for receiving inlet air 14 which preferably enters the inlet at a speed in excess of Mach 1. The shape of inlet cone or body 16 directs the inlet air 14 to a constricted flow path 18 which is formed by the ramjet casing 20 and the inlet body 16.
Upon exiting the constricted flow path 18 the inlet air enters the combustion chamber 22 which is provided with fuel injectors 24 located proximate to flaming elements or burners 26. Fuel exiting from the fuel injectors mixes with the compressed inlet air and the air-fuel mixture is combusted by the burners 26. The combusted air-fuel mixture exits as exhaust from exhaust nozzle 28.
A scramjet or supersonic combustion ramjet is similar in design to a ramjet. However, the airflow in the combustion chamber of a scramjet is supersonic. Accordingly, the air inlet of a scramjet is designed to allow compressed, supersonic airflow to continue into the combustion chamber.
FIG. 2 is a side-view cross-section of an exemplary cylindrically-shaped scramjet engine. The scramjet 30 is provided with a casing 32 within which is situated a center body 34 having an inlet region 36, a combustion region 38 and an exhaust nozzle region 40. An inlet 42 is formed from the inlet region 36 of center body 34 and the forward region 32F of casing 32. The center body 34 is contoured to form a constricted flow path 44 with the casing 32.
Within the constricted flow path 44 is a combustion section 46 which includes (in the liquid fuel-type scramjet) fuel injectors 48 in proximate relation to burners 50. The combusted air-fuel mixture exits the scramjet through the nozzle 52 which is formed from the exhaust nozzle region 40 of the center body 34 and the rearward portion 32R of casing 32.
The National Aeronautic and Space Administration (NASA) has invested heavily in scramjet technology. NASA's X-43A scramjet has been flown at a speed of Mach 9.6 and utilized a Pegasus booster rocket to achieve the hypersonic speeds necessary to initiate scramjet propulsion. Experiments with scramjets have resulted in a belief that the technology will eventually lead to hypersonic commercial aviation.
A problem encountered in the high speed environment of the scramjet has been the inability to efficiently mix air and fuel for optimal combustion. In aeronautics, it has been a typical design goal to achieve laminar airflow over as much of a wing or vehicle surface as possible. (Air that flows smoothly in a continuous stream is laminar, while an air stream that is rough or broken is turbulent. Transitional airflow, as the name implies, alternates or transitions between laminar and turbulent conditions.)
In the prior art, the airflow received in the combustion chamber or combustion section of a SCRAMJET has been laminar or transitional in nature which has resulted in less than optimal mixing and combustion.